Mpg ?

The fuel guage on the Prius is famous for not changing, and then changing suddenly. To be on the safe side, I always fill up when I get down to 1 bar, rather than waiting until it flashes.

 

Hi usinchino,

Welcome to PC. The Gas tank has a rubber bladder which help prevent vapor emissions and limits water condensation into the gas. The bladder is made from rubber, so it expands and shrinks with temperature, and also gets stiffer when cold. So, this can limit how much gas actually makes it into the tank (bladder). The volume of the tank can be as little as 8 gallons in real cold weather.

If you are at one pip on the indicator, get thyself to a gas station now! Many new Prius owners have run out of gas assuming they have 11.9 gallons and the gas gauge is just wrong!

 

several people have done long term tracking of mileage. They calculate how much gas the miles driven and the MFD fuel economy result indicates, and compared that against how much gas was pumped over months. And have found it typically within 1% but in some cases 2 %. When the tank stretches, the mileage by distance and pumped volume goes down, and when the tank shrinks the mileage by distance and pumped volume goes up. Only when the temperature is constant for the whole driving period are the mileage from the MFD and by pumped volume similar.

The conclusion is therefore that the MFD fuel economy is quite close to actual, where by gallons pumped can be well off on any single tank.

 

The colder the temperature is the less the bladder will stretch. Get gas NOW.